System and method for cooling or heating

ABSTRACT

The invention relates to a system for cooling and heating, having a first heat exchanger ( 10 ) for outputting heat to and extracting it from a heat reservoir ( 12 ); a second heat exchanger ( 14 ) for extracting heat from and outputting it into a space ( 16 ) to be cooled or heated; a compressor ( 18 ); an expansion device ( 20 ); and means ( 22, 24 ) for switchover between a cooling mode and a heating mode; wherein the switchover means ( 22, 24 ) are integrated with a module ( 26 ). The invention also relates to a method for switching over between a cooling mode and a heating mode.

[0001] The invention relates to a system for cooling and heating, havinga first heat exchanger for outputting heat to and extracting it from aheat reservoir; a second heat exchanger for extracting heat from andoutputting it into a space to be cooled or heated; a compressor; anexpansion device; and means for switchover between a cooling mode and aheating mode. The invention also relates to a method for switching overbetween a cooling mode and a heating mode by means of a system having afirst heat exchanger for outputting heat into and extracting it from aheat reservoir, a second heat exchanger for extracting heat from andoutputting it into a space to be cooled or heated, a compressor, anexpansion device, and means for switchover between a cooling mode and aheating mode.

PRIOR ART

[0002] Systems and methods of this generic type are known, particularlyfor cooling and heating internal compartments of motor vehicles. Coolingwith such systems and methods using an air conditioner built into amotor vehicle has already been known for a long time. Increasingly,however, heating with such systems is also gaining in importance. Thereason for this is not least the development of engines with optimizedfuel consumption, since in these engines not enough heat is output tothe coolant to heat the vehicle comfortably in low-load operation at lowtemperatures. This is true particularly for direct-injection Dieselengines, which already fundamentally have additional heaters to assurecomfort at low temperatures. Motor vehicles with direct gasolineinjection will in future also have to be equipped with additionalheaters, if a comfortable interior temperature is to be maintained.

[0003] Most vehicles in the top price class and increasingly the middleprice class as well have an air conditioner as standard equipment. Atlow ambient temperatures, the components of such an air conditioner canbe utilized as a heat pump by reversing the heat circulation. Such aheat pump is distinguished by low energy consumption and spontaneousresponse performance at high heating capacity. With a view to safety,window de-icing, and passenger comfort, this is an appropriate conceptfor designing additional heaters for the future.

[0004] In FIGS. 5 and 6, two air conditioner circuits are shown; in FIG.5, a conventional cooling mode is illustrated, while in FIG. 6 a heatingmode is shown, with the components additionally required for the heatingmode.

[0005] In FIG. 5, an air conditioner circuit is shown schematically. Afirst medium enters a first heat exchanger 110 and flows through a loop160. The medium outputs heat to the ambient air 162 and thus coolsitself. From the heat exchanger 110, a cooled medium emerges. Thiscooled medium is now passed through an internal heat exchanger 128,whose function will be explained hereinafter. After the medium hasemerged from the internal heat exchanger 128, it enters an expansiondevice 120. The medium cools down sharply by expansion and is thendelivered to a second heat exchanger 114. In this heat exchanger 114,the cold medium can cool down warm ambient air or circulating air andcan be made available in the form of cold air 164 to a space to becooled, such as the vehicle interior. In this process, the formation ofcondensate 166 occurs. The medium, now re-heated and evaporated becauseof the heat exchange in the heat exchanger 114, emerges from the heatexchanger 114 and then flows through the internal heat exchanger 128again. After emerging from the internal heat exchanger 128, the mediumenters a compressor 118, where by compression it is put at a higherpressure and heated. A heated medium is thus again available, which canenter the first heat exchanger 110 for the purpose of heat exchange. Theloop is closed.

[0006] The internal heat exchanger 128 serves to increase the capacityof the loop. Thus the medium before entering the expansion device 120 iscooled by the returning medium that has emerged from the second heatexchanger 114, while the returning medium is heated by reflux. As aresult of this heat exchange, the proportion of liquid in the fluid uponleaving the expansion device 120 is increased. This increases theefficiency in the loop.

[0007] In FIG. 6, a loop is shown which in comparison with FIG. 5 isequipped with additional components. These components are required inorder to use the loop for heating a space. Once again, the loop will bedescribed beginning at the inflow of the medium into the first heatexchanger 110. Cold medium enters the heat exchanger 110. In the heatexchanger, the cold medium is heated and evaporated by interaction withthe ambient air 162, while the ambient air is cooled down. Depending onthe temperature, the formation of condensate or ice 168 can occur. Afterthe medium flows out of the first heat exchanger, it flows via a firstvalve 170 into the internal heat exchanger 128: After the medium emergesfrom the internal heat exchanger 128, it flows into the compressor 118,where it is compressed and heated. Once the medium has left thecompressor, it flows via a second valve 172 into the second heatexchanger. There, the heated medium can heat cold ambient air or coldcirculating air and thus can be available as useful heat 174 to a spaceto be heated. The medium emerges in the cooled state from the secondheat exchanger 114 and then flows into a third valve 176. This thirdvalve 176 directs the flow of the medium to a fourth valve 178, whereonce again the medium is directed such that it enters the internal heatexchanger 128. After emerging from the internal heat exchanger 128, themedium enters the expansion device 120, where it is cooled by expansion,and then via a valve 178 it is directed into the first heat exchangeragain. The loop of the medium is closed.

[0008] Once again, the internal heat exchanger 128 serves to increasethe capacity. First, the heated medium, which is to be further heated inthe compressor 118, is heated in the internal heat exchanger 128 by thereturning medium, which in turn flows into the internal heat exchangerfrom the second heat exchanger 114. Second, this returning medium,before cooling down by expansion in the expansion device 120, is cooleddown by the medium entering the heat exchanger, which medium has emergedfrom the first heat exchanger 110.

[0009] It can be seen that to achieve a system which makes both acooling mode and a heating mode possible, additional components arerequired. These are in particular the valves 170, 172, 176 and 178,which by means of suitable switchover can form either a heating loop ora cooling loop. Besides the valves 170, 172, 176 and 178, otheradditional components are necessary, such as supplementary lines, whichmeans a further increase in weight and further complication and expense.Also, because of the greater number of requisite lines and above allconnections, the vulnerability to malfunction and in particular theincidence of leaks are increased.

ADVANTAGES OF THE INVENTION

[0010] The invention improves on the generic system by providing thatthe switchover means are integrated with a module. The result is acompact design, in particular with economies in terms of line lengthsand connections that are vulnerable to malfunction, and with less effortand expense for installation. Along with the economy in terms of linesthat carry the coolant medium, the number and length of the electricallines are also reduced, because of the modular structure.

[0011] Preferably, an internal heat exchanger is provided between thefirst heat exchanger and the second heat exchanger. An internal heatexchanger of this kind serves to increase the capacity of the coolingand heating system. In the case of the cooling mode, heated medium whichflows out of the first heat exchanger back to the second heat exchangeris cooled prior to the expansion; for this purpose, the medium flowingfrom the second heat exchanger to the compressor is used. Thetemperature of the medium flowing back and forth is thus advantageouslyprepared for the next event.

[0012] It is especially preferred if the switchover means include afirst valve and a second valve, each having four ports. This is anespecially compact way to realize the invention, since the number ofpressure connections is reduced, and moreover this favors a smalldesign.

[0013] Preferably, the invention is refined in that in the first valve,a first port communicates with the first heat exchanger, a second portcommunicates with the expansion device, a third port communicates withthe internal heat exchanger, and a fourth port communicates with thesecond heat exchanger. In the first valve, this creates theprerequisites for correctly performing the switchover of part of theloop of the medium between the heating mode and the cooling mode.

[0014] The invention is also advantageously refined in that in thesecond valve, a first port communicates with the first heat exchanger, asecond port communicates with the internal heat exchanger, a third portcommunicates with the compressor, and a fourth port communicates withthe second heat exchanger. Thus the second valve is likewise capable ofcontrolling the loops required for both the heating mode and the coolingmode.

[0015] It is advantageous that in the cooling mode, the first port andthe third port of the first valve communicate with one another, and thesecond port and the fourth port of the first valve communicate with oneanother, and that in the cooling mode, the first port and the third portof the second valve communicate with one another, and the second portand the fourth port of the second valve communicate with one another.Thus an adjustment of the valves that makes a cooling mode possible isavailable.

[0016] It is also advantageous that in the heating mode the first portand the second port of the first valve communicate with one another, andthe third port and the fourth port of the first valve communicate withone another; and that in the cooling mode, the first port and the secondport of the second valve communicate with one another, and the thirdport and the fourth port of the second valve communicate with oneanother. In this way, the medium is carried through the system in theway that is advantageous for the heating mode.

[0017] It is especially useful if the switchover means are actuatable atleast in part by a common drive mechanism. This reduces the number ofrequired components.

[0018] In this conjunction, it can be especially advantageous if theswitchover means are actuatable at least partly by a hydraulic orpneumatic drive mechanism, for instance with the refrigerant. Ahydraulic or pneumatic drive mechanism of this kind can be supplieddirectly or indirectly by means of a pressure difference of therefrigerant at the compressor. For this triggering, a very small magnetvalve suffices.

[0019] It is also useful if the internal heat exchanger is integratedwith the module. Because not only the switchover means, for instance,but also the heat exchanger are integrated, a further reduction in thestructural size is achieved.

[0020] For the same reason, it can be useful if the expansion device isintegrated with the module. This has the advantage, among others, thatonce again a further reduction in size is achieved, which also shortensthe hydraulic courses.

[0021] It is especially useful if the compressor is integrated with themodule. This too can lead to a further reduction in size of the system.

[0022] Usefully, a collector can be integrated with the module. Insystems with a collector, integrating this component can likewisereinforce the advantages of the invention.

[0023] For the same reason, it can be useful if an oil filter isintegrated with the module.

[0024] Also in a useful way, a hot-gas bypass valve is integrated withthe module, which can serve to de-Ice the outside air heat exchanger.

[0025] Still another integrating provision is made available within thescope of the invention by providing that pressure sensors are integratedwith the module. These can serve to sense both the high and the lowpressure. By integrating a control unit for all the valves and for thecompressor with the module, the external electrical installation effortand expense can be reduced.

[0026] It is especially advantageous if at least some of the componentsthat can be integrated with the module are disposed in a common pressurehousing. By means of such a common pressure housing, the tightness ofthe module and thus of the air conditioner can be increased. Because acommon pressure housing is used, materials can be used inside thepressure housing that could not be used until now, because of the greatpressure differences. For instance, it is conceivable to use plastics.It is also possible for lines that are under pressure to be designedwith thinner wall thicknesses, so that in this way as well, additionalweight can be saved.

[0027] The invention exhibits its particular advantages within thecontext of a system in which CO₂ is provided as the medium for thecooling loop and heating loop. Such CO₂-based cooling systems willbecome increasingly important in the future, since in them aconventional refrigerant is replaced by a substance that presents noproblems whatever of disposal, namely CO₂. Especially because of thepossibilities of increasing the capacity by means of an internal heatexchanger, the invention is especially useful in conjunction with CO₂ asa coolant and heating agent.

[0028] The invention improves on the generic method by providing thatthe switchover means are integrated with a module. As a result, a methodon the basis of a compact design is available, in which in particularthe line lengths and weight are reduced, as are the effort and expenseof installation. Along with the economy in terms of lines that carry thecooling medium, the number and length of electrical lines can also bereduced because of the modular structure.

[0029] Preferably, the method of the invention is refined in that heatis exchanged in an internal heat exchanger, which is disposed betweenthe first heat exchanger and the second heat exchanger. Such an internalheat exchanger serves to increase the capacity of the cooling andheating system. In the case of the cooling mode, heated medium whichflows back out of the second heat exchanger to the first heat exchangeris preheated before the compression, and for this purpose, the mediumflowing from the first heat exchanger to the expansion device is used.The temperature of the medium flowing back and forth is accordinglyadvantageously prepared for the next event.

[0030] The method of the invention is especially advantageously refinedin that the switchover means include a first valve and a second valve,each having four ports; that in the first valve, a first portcommunicates with the first heat exchanger, a second port communicateswith the expansion device, a third port communicates with the internalheat exchanger, and a fourth port communicates with the second heatexchanger; that in the second valve, a first port communicates with thefirst heat exchanger, a second port communicates with the internal heatexchanger, a third port communicates with the compressor, and a fourthport communicates with the second heat exchanger; that a switchover tothe cooling mode is made by causing the first port and the third port ofthe first valve to communicate with one another and causing and thesecond port and the fourth port of the first valve to communicate withone another, and by causing the first port and the third port of thesecond valve to communicate with one another, and causing and the secondport and the fourth port of the second valve to communicate with oneanother. In the first valve, this creates the prerequisites forcorrectly performing the switchover of part of the loop of the mediumbetween the heating mode and the cooling mode.

[0031] Preferably, a switchover to the heating mode is made by causingthe first port and the second port of the first valve to communicatewith one another, and causing the third port and the fourth port of thefirst valve to communicate with one another, and by causing the firstport and the second port of the second valve to communicate with oneanother and causing the third port and the fourth port of the secondvalve to communicate with one another. Thus the second valve is likewisecapable of controlling the loops required for both the heating mode andthe cooling mode.

[0032] It is preferred that the switchover means are actuatable at leastin part by a common drive mechanism. This reduces the number of requiredcomponents.

[0033] It is likewise useful if the switchover means are actuatable atleast in part by a hydraulic drive mechanism. For this triggering, avery small magnet valve suffices.

[0034] Preferably, CO₂ is provided as the medium for the cooling loopand heating loop. Such cooling systems on the basis of CO₂ will gainincreasing significance in future, since a conventional refrigerant isreplaced with a substance, namely CO₂ that can be disposed of withoutproblems. Especially because of the capabilities of increasing thecapacity by means of an internal heat exchanger, the invention inconjunction with CO₂ as a coolant and heating agent are especiallyuseful.

[0035] Preferably, the internal heat exchanger is constructed byμ-structuring. Especially if CO₂ is the refrigerant, combining thecomponents in the module 26 makes it possible to use components of theμ-structured type, since as a result the pressure losses inside themodule are sufficiently low.

[0036] The invention is based on the surprising discovery that theswitchover function between a cooling mode and a heating mode can beachieved with a compact design. By furnishing a module which containsessential components of the system, the number of pressure connections,the number of hydraulic lines, the number of electrical lines, and othereffort and expense can all be reduced. Furthermore, the structural sizeis reduced and weight is saved.

DRAWINGS

[0037] The invention will now be described in terms of preferredembodiments as examples, in conjunction with the accompanying drawings.

[0038] Shown are:

[0039]FIG. 1, a schematic illustration of a first embodiment of theinvention;

[0040]FIG. 2, a schematic illustration of the first embodiment of theinvention in a modified mode of operation;

[0041]FIG. 3, a schematic illustration of a third embodiment of theinvention;

[0042]FIG. 4, a schematic illustration of a fourth embodiment of theinvention;

[0043]FIG. 5, a schematic illustration of a first embodiment in theprior art; and

[0044]FIG. 6, a schematic illustration of a second embodiment in theprior art.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0045] In the ensuing description of the drawings, components that arethe same or comparable will be identified by the same referencenumerals.

[0046]FIG. 1 shows a schematic illustration of a system according to theinvention for cooling and heating. The switchable components of thesystem are switched, in the illustration of FIG. 1, in such a way thatthe system is in the cooling mode. A medium is introduced into the firstheat exchanger 10. In the heat exchanger, an exchange of heat takesplace between a heat reservoir 12 and the introduced medium, so thatambient air 62 is heated, and the medium is cooled in reflux. The cooledmedium leaves the first heat exchanger 10 and then enters a module 26.

[0047] The events that take place in the module 26 will be describedhereinafter.

[0048] The medium emerges from the module 26 in cooled form and thenenters a second heat exchanger 14. In this second heat exchanger,ambient air or circulating air also enters, so that an air flow 74 thatis cooled in the heat exchanger 14 enters the space 16 to be cooled.This creates condensate 66. The medium, heated and evaporated because ofthe cooling of the ambient air or circulating air 74 emerges from thesecond heat exchanger 14. Next, the medium enters the module 26. In thismodule, the medium is heated and brought to a higher pressure. From themodule 26, heated and compressed medium then emerges, so that it can bereturned to the first heat exchanger again. The loop is closed.

[0049] Integrated with the module 26 are a plurality of components whichare essential to the operation of the system. The module 26 includes afirst valve 22, with a first port 30, a second port 32, a third port 34,and a fourth port 36. The module 26 further includes a second valve 24,with a first port 38, a second port 40, a third port 42, and a fourthport 44. The module 26 further includes a compressor 18, an expansiondevice 20, and an internal heat exchanger 28. In FIG. 1, the first valve22 and the second valve 24 are switched in such a way that the system isin the cooling mode. If the medium cooled in the first heat exchanger 10now enters the module 26 and thus the first valve 22, then it firstreaches the first port 30. The first port 30 communicates with the thirdport 34. The third port 34 communicates with the internal heat exchanger28. The medium is thus conducted into the internal heat exchanger 28,whose function will be described hereinafter. After the medium emergesfrom the internal heat exchanger 28, it enters an expansion device 20.In this expansion device 20, the medium is expanded and thus cooled. Themedium emerging from the expansion device 20 reaches the second port 32of the valve 22, which port communicates with the expansion device 20.The second port 32 communicates with the fourth port 36 of the firstvalve, so that the medium is carried to the fourth port 36. From there,the medium emerges from the module 26 and enters the second heatexchanger 14.

[0050] In the return of the medium, the medium again flows through themodule 26. The medium enters the module 26, where it first reaches thefourth port 44 of the second valve. The fourth port 44 of the secondvalve 24 communicates with the second port 40 of the second valve 24.The medium is thus carried to the second port 40 of the second valve 24,and from there it is carried to the internal heat exchanger 28, whichcommunicates with the second port 40 of the second valve 24. Afterpassing through the internal heat exchanger, the medium emerges from theinternal heat exchanger 28 and reaches a compressor 18. In thiscompressor 18, the medium is heated and compressed. The outlet of thecompressor communicates with the third port 42 of the second valve. Inthe present switching state, the third port 42 communicates with thefirst port 38 of the second valve 24. The medium is thus carried fromthe third port 42 of the second valve 24 to the first port 38 of thesecond valve 24. The first port communicates with the first heatexchanger 10, so that the medium emerges from the module 26 and canreach the first heat exchanger 10.

[0051] Particularly if the system is operated with CO₂ as the coolingmedium, it proves useful to provide an internal heat exchanger 28. Thisinternal heat exchanger serves to increase the capacity. The mediumflowing into the expansion device 20 is cooled by the returned medium.In reflux, the returned medium, which flows into the compressor 18, isheated by the inflowing medium.

[0052] It can be seen from FIG. 1 that only four external pressureconnections are needed for the module 26, namely the first port 30 ofthe first valve 22 for the communication with the first heat exchanger10; the third port 36 of the first valve 22 for the communication of thefirst valve 22 with the second heat exchanger 14. The first port 38 ofthe second valve 24 for the communication of the second valve 24 withthe first heat exchanger 10; and the fourth port 44 of the second valve24 for the communication of the second valve 24 with the second heatexchanger 14. Thus in comparison to the embodiment of FIG. 6, forinstance, which has been explained in the description of the prior art,considerable economies in terms of line lengths are achieved. The effortand expense of installation are also reduced.

[0053] It also conceivable for the compressor 18 not to be integratedwith the module 26. In such an arrangement, the module 26 should beequipped with two further pressure connections, which once again stillreduces the complexity of the hydraulic circuitry considerably.Moreover, the components can be integrated either entirely or partly inone block. Thus a compact representation of the module can be achieved.A tight embodiment can thus be made possible in a simpler way.

[0054] In FIG. 2, the system of FIG. 1 is shown in a different switchingstate. The system of FIG. 2 is in the heating mode. The switchover fromthe cooling mode of FIG. 1 to the heating mode of FIG. 2 is done byswitchover of the first valve 22 and the second valve 24. In the firstvalve 22, the first port 30 now communicates with the second port 32.The third port 34 of the first valve 22 communicates with the fourthport 36 of the first valve 22. In the second valve 24, the first port 38communicates with the second port 40. The third port 42 communicateswith the fourth port 44. If cold medium now flows into the first heatexchanger 10, it absorbs heat from the heat reservoir 12, so that theambient air 62 is cooled down. This can produce condensate or ice 68.After the first medium emerges from the first heat exchanger 10, themedium enters the module 26 in the heated state. There, it reaches thefirst port 38 of the second valve 24. The first port 38 communicateswith the second port 40, which communicates with the internal heatexchanger 28. The medium is thus carried to the internal heat exchanger28. After the medium has passed through the internal heat exchanger 28,it enters the compressor 18, and then it reaches the third port 42 ofthe second valve 24. This third port 42 of the second valve 24communicates with the fourth port 44 of the second valve 24, which portis in communication with the second heat exchanger 14. Thus the mediumpasses in the heated state from the compressor 18 to reach the secondheat exchanger 14. In this second heat exchanger, ambient air orcirculating air is heated, so that finally, warm air 24 can be output toa space 16 to be heated. In the process, the medium cools down. Thecooled medium is returned to the module 26. There, the medium firstreaches the fourth port 36 of the first valve 22. The fourth port 36 ofthe first valve 22 communicates with the third port 34 of the firstvalve 22. This fourth port 34 is in communication with the internal heatexchanger 28. Thus from the second heat exchanger 14, the medium reachesthe internal heat exchanger 28. After the medium passes through theinternal heat exchanger 28, it enters the expansion device 20, where itexpands and cools down. After emerging from the expansion device 20, themedium reaches the second port 32 of the first valve 22. The second port32 communicates with the first port 30 of the first valve 22, which isin communication with the first heat exchanger 10. Thus from theexpansion device 20, the medium passes in the cooled state via thesecond port 32 and the first port 30 of the first valve 22 to reach thefirst heat exchanger 10. The loop is closed.

[0055] Once again, in the heating mode as well, the internal heatexchanger 28 serves to increase the capacity, which is especiallypreferable in operation using CO₂ as the medium. Before entering thecompressor and the internal heat exchanger 28, the medium is heated,which occurs by the interaction with the returning medium from thesecond heat exchanger 14. In reflux, the returning medium is cooleddown, before the expansion in the expansion device 20, by interactionwith the inflowing medium.

[0056] The switchover between the switching states of FIG. 1 and FIG. 2can be done in a rational way such that common drive mechanisms can beused for those elements that are to be switched simultaneously. Thisreduces the switching complexity and also the weight of the module 26and thus of the entire system. It can be especially advantageous thatfor triggering the valves a hydraulic drive mechanism is used, which issupplied by the pressure difference at the compressor. For triggeringsuch a hydraulic mechanism, either a single or several very small magnetvalves can be used. The apparatus of FIGS. 1 and 2 can also be refinedsuch that pressure sensors for high and low pressure are also integratedwith the module 26.

[0057] In FIG. 3, a further schematic illustration of a system of theinvention is shown. It corresponds largely to what is shown in FIG. 2.In addition to FIG. 2, a collector 46 is integrated with the module 26;in the heating mode shown, this collector is disposed on the inlet sideof the internal heat exchanger 28, and it communicates with the secondport 40 of the first valve 24. The collector 46 serves both to keeprefrigerant on hand and to separate liquid from the gas that can enterthe module 26. An advantageous embodiment provides that all or somecomponents of the module 26 are integrated in a pressure vessel, whichthen acts as a collector. This not only makes for economy in terms ofinstallation space, but above all the sealing off of the components fromthe outside can be performed by the pressure vessel. This makeslow-leakage manufacture of the module 26 much easier.

[0058] In FIG. 4, a further schematic illustration of a system of theinvention is shown. In addition to the components of FIG. 3, it has ahot-gas bypass valve 50. This valve 50 connects the inlet side to theoutlet side of the second heat exchanger 14. This valve 50, too, can beintegrated with the module 26. The system is shown in a switching statefor hot-gas/thawing operating mode. Short-circuiting the heat exchanger14 by means of the valve 50 means that a large proportion of the fluidfrom the expansion device 20 reaches the valve 24 directly. As a result,virtually no heat is transferred in the heat exchanger 14. The wasteheat from the system is output by the fluid completely in the heatexchanger 10. As a result, ice located on the air side of this heatexchanger can be blasted off or melted.

[0059] The above description of the exemplary embodiments of the presentinvention is intended for solely illustrative purposes and not for thesake of limiting the invention. Within the scope of the invention,various changes and modifications may be made without departing from thescope of the invention and its equivalents.

1. A system for cooling and heating, having a first heat exchanger (10)for outputting heat to and extracting it from a heat reservoir (12), asecond heat exchanger (14) for extracting heat from and outputting itinto into a space (16) to be cooled or heated, a compressor (18), anexpansion device (20), and means (22, 24) for switchover between acooling mode and a heating mode, characterized in that the switchovermeans (22, 24) are integrated with a module (26).
 2. The system of claim1, characterized in that an internal heat exchanger (28) is providedbetween the first heat exchanger (10) and the second heat exchanger(14).
 3. The system of claim 1 or 2, characterized in that theswitchover means include a first valve (22) and a second valve (24),each having four ports (30, 32, 34, 36; 38, 40, 42, 44).
 4. The systemof one of the foregoing claims, characterized in that in the first valve(22) a first port (30) communicates with the first heat exchanger (10),a second port (32) communicates with the expansion device (20), a thirdport (34) communicates with the internal heat exchanger (28); and afourth port (36) communicates with the second heat exchanger (14). 5.The system of one of the foregoing claims, characterized in that in thesecond valve (24) a first port (38) communicates with the first heatexchanger (10), a second port (40) communicates with the expansiondevice (20), a third port (42) communicates with the internal heatexchanger (28); and a fourth port (44) communicates with the second heatexchanger (14).
 6. The system of one of the foregoing claims,characterized in that in the cooling mode, the first port (30) and thethird port (34) of the first valve (22) communicate with one another,and the second port (32) and the fourth port (36) of the first valve(22) communicate with one another; and in the cooling mode, the firstport (38) and the third port (42) of the second valve (24) communicatewith one another, and the second port (40) and the fourth port (44) ofthe second valve (24) communicate with one another.
 7. The system of oneof the foregoing claims, characterized in that in the heating mode thefirst port (30) and the second port (32) of the first valve (22)communicate with one another, and the third port (34) and the fourthport (36) of the first valve (22) communicate with one another; and inthe cooling mode, the first port (38) and the second port (40) of thesecond valve (24) communicate with one another, and the third port (42)and the fourth port (44) of the second valve (24) communicate with oneanother.
 8. The system of one of the foregoing claims, characterized inthat the switchover means (22, 24) are actuatable at least in part by acommon drive mechanism.
 9. The system of one of the foregoing claims,characterized in that the switchover means (22, 24) are actuatable atleast in part by a hydraulic drive mechanism.
 10. The system of claim 9,characterized in that the hydraulic drive mechanism is supplied by thepressure difference upstream and downstream of the compressor.
 11. Thesystem of one of the foregoing claims, characterized in that theinternal heat exchanger (28) is integrated with the module (26).
 12. Thesystem of one of the foregoing claims, characterized in that theexpansion device (20) is integrated with the module (26).
 13. The systemof one of the foregoing claims, characterized in that the compressor(18) is integrated with the module (26).
 14. The system of one of theforegoing claims, characterized in that a collector (46) is integratedwith the module (26).
 15. The system of one of the foregoing claims,characterized in that an oil filter is integrated with the module (26).16. The system of one of the foregoing claims, characterized in that ahot-gas bypass valve (50) is integrated with the module (26).
 17. Thesystem of one of the foregoing claims, characterized in that pressuresensors are integrated with the module (26).
 18. The system of one ofthe foregoing claims, characterized in that the controller of the valvesis integrated with the module (26).
 19. The system of one of theforegoing claims, characterized in that at least some of the componentsthat can be integrated with the module (26) are disposed in a commonpressure housing.
 20. The system of one of the foregoing claims,characterized in that at least some of the components that can beintegrated with the module (26) are disposed in a common pressurehousing embodied as a collector.
 21. The system of one of the foregoingclaims, characterized in that CO₂ is provided as the medium for thecooling loop and heating loop.
 22. The system of one of the foregoingclaims, characterized in that the internal heat exchanger (28) isconstructed by μ-structuring.
 23. A method for switchover between acooling mode and a heating mode by means of a system having a first heatexchanger (10) for outputting heat into and extracting it from a heatreservoir (12), a second heat exchanger (14) for extracting heat fromand outputting it into a space (16) to be cooled or heated, a compressor(18), an expansion device (20), and means (22, 24) for switchoverbetween a cooling mode and a heating mode, characterized in that theswitchover means (22, 24) are integrated with a module (26).
 24. Themethod of claim 19, characterized in that heat is exchanged in aninternal heat exchanger (28), which is disposed between the first heatexchanger (10) and the second heat exchanger (14).
 25. The method ofclaim 19 or 20, characterized in that the switchover means include afirst valve (22) and a second valve (24), each having four ports (30,32, 34, 36; 38, 40, 42, 44); that in the first valve (22), a first port(30) communicates with the first heat exchanger (10), a second port (32)communicates with the expansion device (20), a third port (34)communicates with the internal heat exchanger (28), and a fourth port(36) communicates with the second heat exchanger (14); that in thesecond valve (24), a first port (38) communicates with the first heatexchanger (10), a second port (40) communicates with the internal heatexchanger (28), a third port (42) communicates with the compressor (18),and a fourth port (44) communicates with the second heat exchanger (14);that a switchover to the cooling mode is made by causing the first port(30) and the third port (34) of the first valve (22) to communicate withone another, and causing the second port (32) and the fourth port (36)of the first valve (22) to communicate with one another, and by causingthe first port (38) and the third port (42) of the second valve (24) tocommunicate with one another, and causing the second port (40) and thefourth port (44) of the second valve (24) to communicate with oneanother.
 26. The method of one of claims 19-21, characterized in that aswitchover to the heating mode is made by causing the first port (30)and the second port (32) of the first valve (22) to communicate with oneanother, and causing the third port (34) and the fourth port (36) of thefirst valve (22) to communicate with one another, and by causing thefirst port (38) and the second port (40) of the second valve (24) tocommunicate with one another, and causing the third port (42) and thefourth port (44) of the second valve (24) to communicate with oneanother.
 27. The system of one of claims 19-22, characterized in thatthe switchover means (22, 24) are actuatable at least in part by acommon drive mechanism.
 28. The system of one of claims 19-23,characterized in that the switchover means are actuatable at least inpart by a hydraulic drive mechanism.
 29. The system of one of claims19-24, characterized in that CO₂ is provided as the medium for thecooling loop and heating loop.